The present invention pertains to a vibratory exciter unit that is adapted for interchangeable connection to a number of diverse vibratory tools and for vibration isolating connection to a tool carrier.
Many types of soil excavation, compaction and other construction activities utilize vibratory tools of various types to facilitate the particular activity. Such vibratory tools include compaction rollers, compaction plates, vibratory plows, asphalt cutters, concrete breakers and pile and sheet drivers and extractors. Such vibratory tools are often connected to the boom of an excavator or similar off-the-road vehicle such that the boom can be operated to place, maneuver, and apply downpressure to the tool during use. It is important to isolate the vibratory tool from the excavator boom and the machine that operates the boom. It is known in the art to provide elastomer isolators between the boom and the exciter unit, as shown for example in U.S. Pat. No. 5,244,306 which is incorporated by reference herein.
Because of the wide variety of vibratory tools that are made for attachment to an excavator or the like, special connectors and attaching arrangements are often needed to adapt a particular manufacturer's vibratory tool to the boom of an excavator made by a different manufacturer. The typical connection between an excavator boom and a vibratory tool includes a connecting link attached to the boom with two pivot pins, the link is also connected with vibration isolating mounts to the vibratory tool. Differences in boom sizes and connecting pin lengths and diameters require the manufacturers of many vibratory tools to stock a large number of parts to accommodate the connections. With respect to the vibratory tool itself, typically connected to the bottom of the connector mechanism, there is little or no interchangeability when changing from one vibratory tool to another.
Elastomer vibration isolators that operate in shear have long been used, but are not very effective and are subject to failure in high load applications. It is also known in the prior art to use elastomer vibration isolators of an annular construction that operate in compression. Both types may be made from material having a flexibility (durometer) that is a compromise between those applications best handled with softer elastomer materials and applications better handled with harder elastomer vibration isolators. For example, in compacting sand or more granular materials, high amplitude and lower load compaction is preferable, whereas in compacting clay and similar materials, high load, low amplitude vibrations are preferable. It has also been found that in using annular elastomer vibration isolators in high vertical load applications, the elastomer mounts are subject to unacceptably high compression forces as a result of being compressed past their design limits. This often results in destruction of the isolator by loss of the bond by which the isolator is attached to the metal parts to which it is bonded. This results in loss of isolation and the transfer of vibrations back to the boom and to the vehicle to which it is attached